If `services.samba.enable` is true, the the samba Module already adds the samba Package. If a User sets a differnet Package in `services.samba.package` then `environment.systemPackages` will contain two different samba Packages.
```
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/testparm' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/testparm'
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/testparm' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/testparm'
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/nmbd' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/nmbd'
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/nmbd' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/nmbd'
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/smbcontrol' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/smbcontrol'
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/smbcontrol' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/smbcontrol'
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/gentest' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/gentest'
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/gentest' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/gentest'
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/smbpasswd' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/smbpasswd'
system-path> warning: collision between `/nix/store/rw5fzn10lb21xk3myc0d4m49j69d0crs-samba-4.19.2/bin/smbd' and `/nix/store/ssxn9pnl293knqghcjvpbzb6ysg0f7fv-samba-4.19.2/bin/smbd'
...
```
(The original samba will still stay in the closure as `kdenetwork-filesharing` depends on it.)
In https://github.com/NixOS/nixpkgs/pull/254071, a mismatch between usage of
the Nix language and the NixOS module system was introduced. By merging the
kwin_wayland wrapper attrset into the mkIf representation, the former was
effectively ignored.
As a result, the capability wrapper for kwin_wayland stopped being installed,
leading to realtime scheduling being disabled. The issue was not detected
because the behavioral change is very subtle.
By consistently using language-level constructs, this mismatch is resolved.
The capability wrapper is thus installed again and realtime scheduling is
restored.
[Motivation](https://github.com/NixOS/nixpkgs/issues/257817#issuecomment-1741705042):
- Having all the XKB options in the same attribute set clarifies their
relation better than using a common option name prefix ("xkb").
- `services.xserver.layout` is an XKB option, but this is not obvious
from its name. Putting it with the other XKB options clarifies this.
Co-authored-by: Michele Guerini Rocco <rnhmjoj@users.noreply.github.com>
